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Robotic Hand Gives User A Sense Of Touch

July 25, 2019

A man who lost his hand 17 years ago has been given the sense of touch through a brain-controlled robotic prosthetic.

Keven Walgamott, whose arm was amputated below the elbow after an accident, can now feel 119 different touch sensations through the prosthetic as if it were his own limb.

He is able to distinguish between large, small, soft and hard objects when blindfolded, and handle delicate objects such as grapes and eggs. Everyday tasks such as putting on his wedding ring, peeling a banana or holding a mobile phone are now possible.

“The most amazing thing for me is what the team was able to do,” said Walgamott. “[They] take a bunch of mechanical pieces and provide, through a computer, not only the ability to move all fingers and grasp things but be able to feel again.”

The prosthetic hand and wrist has been in development for 15 years. Electrodes were implanted in the remaining part of his arm, allowing communication between the prosthetic hand and his brain. The hand can move in six directions and is equipped with 19 sensors that detect touch and positioning.

The arrays interpret the signals Walgamott’s brain sends to his arm nerves, and a computer outside the body translates these into digital information, which then instructs the prosthetic to move as the wearer intends. They also provide Walgamott’s nerves with computer-generated touch signals from the prosthesis, which are then interpreted by his brain.

The breakthrough by a team at the University of Utah, published in Science Robotics, was to supply Walgamott’s brain with electrical signals more closely matched to those that would be sent by nerves from a human hand. “If we communicate with the body in the body’s natural language, that information becomes more useful,” said Dr Jake George, a graduate research fellow and the lead author of the paper.

Next, the team plan to expand the sensory information available to the wearer, including pain and temperature. Furthermore, since the prototype requires tethering to a stationary computer, they are developing a portable system and hope that in the next two years test subjects will be able to take the hand home to use.

Aside from the technical hurdles facing the group, George said “one of the next challenges … is to convince insurance companies that this technology is going to be worth the money”. He is hopeful that testimonials from early users such as Walgamott could serve as evidence for the personal and psychological benefits of the prosthesis.

However, Dr Sarah Wilkes, a research fellow at UCL’s Institute of Making who was not involved in the work, said more research would need to be done on the emotional aspect of these types of advanced prosthetics.

“This technology would benefit from rigorous psychosocial research on the users’ emotional responses,” she said. “In our work on material preferences in prosthetics, we interviewed 32 prosthetics users about their relationship with their limb. We found that silicone rubber – the most commonly used material in prosthetics – was very divisive: about half of the users liked it but the others hated it, and that’s problematic. This shows that it’s important that new technologies are centred around the needs and desires of the end users.”

Asked why he had taken part in the study, Walgamott said: “I have friends who are double hand amputees. I get along quite well with just one hand, but they could certainly use the help. For them and for future people, I went ahead and did it. I hope this work will provide a springboard to future enhancements for prosthetic hand use.”

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